This invention relates to field sprayers and more particularly to an automatically extendable and foldable sprayer that provides for both broad swath application of liquid chemical solutions in an extended or working position or condition and for narrow width in a transport position or condition, including means to vary the sprayers from one such position or condition to the other, from the operator's normal working position at motive power controls, simply by advancing or reversing the sprayer along its normal line of travel.
Essential elements of a field sprayer generally are:
1. Spray nozzles which eject liquid spray at spaced points along the length of a spray tube. PA0 2. Spray tubes, which carry liquid to be sprayed, from a manifold or pump to all points along the length of a spray boom which extends across the width of an area to be sprayed. PA0 3. A spray boom which supports the spray tubes and can be moved to adjust the height of the spray tubes and their spray nozzles relative to the ground, so that spray can be ejected at a height appropriate to the area or material being sprayed. PA0 4. A main boom or support boom which carries the weight of the foregoing elements and supports it on wheels which are impelled across the ground by a suitable motive power source, e.g. tractor or truck, with the boom in either working position or in transport position. Because working width of the sprayer may be up to 30 meters or more, provision must be made for transportation of the boom in the direction of its longitudinal axis. PA0 (a) a wheeled motive power source for drawing the sprayer over the ground, PA0 (b) a main boom having (i) a center section, longitudinally aligned transverse to the line of travel of the sprayer and rigidly attached behind said power source and (ii) at least one wing section at each end of the center section, each wing section being offset from direct alignment with the center section and sections adjacent the center section being hingedly attached thereto by a respective universal hinge having a vertical axis and a horizontal axis, theoretical extensions of said axes intersecting at a point hereinafter designated, said wing sections being adapted for additional wheel support and foldable between a working position, aligned parallel with but offset from the center section, and a transport position at right angles to the center section; PA0 (c) a spray boom having a center section and aligned wing sections corresponding to each of said main boom sections respectively and rotatably secured thereto in close parallel relation, said spray boom sections being rotatable about the axis of said alignment and flexibly linked by universal joints, the intersection of the axes of rotation of each said joint being the point of intersection of the aforesaid extensions of the respective main boom universal hinge axes, PA0 (d) sections of spray tube, each one rotatably attached to a corresponding spray boom section in spaced parallel relation to be rotated by rotation of the spray boom about the rotation axis of the spray boom, said spray tube sections being linked by flexible connections to a supply, on said motive power source, of liquid to be sprayed, PA0 (e) a plurality of spray nozzles at spaced points along the length of the spray tubes to eject liquid spray, PA0 (f) wheel means supporting each of said wing sections of said main boom substantially parallel to the ground, each said wheel means being adapted to engage the ground and support its respective wing section by a castor mounting in a castoring mode when the main boom wing sections are hinged in said working position and at least one of said castor mountings on each side of the center section being arranged to lock into a non-castoring mode when the main boom wing sections are folded into the transport position, PA0 (g) power means on said motive power source to rotate the spray boom center section and its spray tube section between a working position, in which the spray tube is held at an adjustable elevation substantially beside the spray boom, and a transport position, in which the spray tube is held substantially vertically above the spray boom, said center section simultaneously rotating the spray boom wing sections between their working position and transport position, PA0 (h) means responsive to the movement of the spray boom between its transport and working positions to lock and release the wheel means into non-castoring and castoring modes respectively, PA0 (i) a rigid boom draw means for each main boom wing section adjacent the center section, each said draw means being pivotally connected at the back end thereof to the respective wing section and having a front end adapted to move between a transport position, in which said front end is carried by the motive power source with no load thereon, and a working position in which the front end is releasably latched into a latched position on the motive power source to draw a load, and PA0 (j) connecting means, responsive to movement of said spray boom center section from its working position to its transport position, to release the front ends of the rigid boom draws from their latched position.
The prior art provides for height of spray variation by rotation of the spray boom about its longitudinal axis. Spray nozzles offset from this axis are raised or lowered accordingly. To obtain maximum stability of the associated main boom during transportation, the wheels must be fixed (non-castoring) wheels, but to prevent "scrubbing" or dragging of wheels when turning in the extended working position, it is necessary to have castoring wheels.
Such prior field sprayers were not automatically or readily foldable to achieve the narrow transport width necessary to transport the device through gates or along roadways and simultaneously retain the necessary rigidity in the boom structure. The operator was required to stop the tractor, dismount and remove a fastener in order to fold the implement into the transport position. Furthermore, the height of the working parts of the implement generally was not adjustable from the tractor while underway although some are now hydraulically adjustable.
My prior invention provided a field sprayer with a multiple section boom that could be extended to cover a wide swath in working position and could be folded to achieve narrow width in a transport position, the extension and folding operations being entirely operable from the operator's control position at the motive power controls of the equipment. Furthermore, the invention provided for powered adjustment of the spray height while in use without loss of overall rigidity or uniformity but required sets of both castoring field wheels and non-castoring transportation wheels to support the folding sections of the main boom. Powered rotation of the main boom transferred the weight of the folding sections of the main boom from the field wheels and engaged a separate set of transport wheels with the ground surface, cleared the sprayer nozzles and associated parts from interference on folding, and released the boom draws or boom pull braces for folding of the main and spray booms.
It has now been found that it is not necessary to rotate a main boom supporting a spray boom in order to obtain rotation of the spray boom; a spray boom can be supported on a main boom and rotated on its spray boom axis by powered means without rotating the supporting main boom, thereby obviating the need for an alternate set of supporting wheels for main boom folding sections when they are to be folded from a working position to a transport position. Powered means on a motive power source is used to rotate linked spray boom sections between a transport position, in which the spray boom holds spray tube sections parallel to and substantially vertically above the corresponding spray boom sections, and a working position, in which the spray boom holds the spray tube sections at an adjustable elevation substantially beside the spray boom. The main boom sections are linked by universal hinges that permit folding of the main boom in a horizontal plane between working and transport positions, and also permit flexing of the wing sections thereof in a vertical direction as the wing section supporting wheels rise and fall in passing over uneven ground. Similarly, the spray boom sections are linked by universal joints that enable rotation of the sections by powered means and at the same time permit both (a) flexing of the spray boom wing sections in a vertical direction as the respective supporting wheels rise and fall and (b) folding of the spray boom wing sections as their respective main boom sections fold in a horizontal plane between working and transport positions.